1. Field of the Invention
The present invention relates to electrically powered door operating equipment used to open and close doors on a variety of light and medium duty shuttle and utility buses. Specifically, the present invention relates to an electric swing plug door operator with a remotely powered auxiliary lock mechanism, door striker, catch, and manual release arrangement adapted for use with medium duty shuttle and utility vehicles.
2. Description of Related Art
Various types of door closing systems are known. Examples of these known systems are described in U.S. Pat. Nos. 4,282,686; 4,924,625 and 5,263,280.
A particular door closing system is the pneumatic rotary operator, which employs a double acting cylinder driving a set of cam followers that ride along opposing helical cam surfaces to convert linear motion to rotational motion. The helical cam surfaces are machined on inner and outer cylindrical nested sleeves. The outer helix is fixed relative to the bus structure while the inner helix, along with a spindle, can rotate. This type of operator employs a spindle lock feature that constrains the rotary drive's spindle from rotating when the drive cam followers are in the fully locked position. The locking feature is a vertical notch that is integral with the outer, stationary helix sleeve. In the fully locked position, the cam followers are driven, under pressure, into the notch transition to constrain the spindle from rotating. This locking method does not engage and lock the door directly and is very sensitive to proper door alignment with the portal opening as well as proper door preload adjustment. The operator may close the door but will not reach the locked position of the door if these adjustments are not executed correctly. Furthermore, if this system should experience sudden loss of air pressure due to an air system component failure, the operator will inadvertently unlock allowing a passenger to push the door or doors manually.
Another known door closing system is the pneumatic rotary operator with a lift and lock feature, which converts the linear motion of a double acting pneumatic cylinder to rotary motion using an opposing helix arrangement similar to the pneumatic rotary operator arrangement discussed above. A differentiating feature of the pneumatic rotary operator with the lift and lock feature is its ability to stop spindle rotation and translate the door panel and associated linkage vertically by approximately 10 mm once the door reaches its closed position. A series of wedges on the door panel leading and trailing edges, engage with corresponding wedges on the door portal as the door is raised to lock the door. Although this method locks the door directly, proper operation of this system relies substantially on proper door panel alignment with the portal opening. Furthermore, should this system experience a sudden loss of air pressure due to an air system failure, the operator will allow the door to drop, thus disengaging the locking wedges and allowing a passenger to manually push the door or doors open. Another potential shortcoming of this design is possible binding of the locking wedges in the door-closed position caused by improper door alignment, plastic deformation, or elastic deformation of the portal opening. Structural deformation of the portal opening may occur when the vehicle is loaded with passengers or if the vehicle sustains collision damage in the general area of the doorway. The binding of the locking wedges may prevent a passenger from manually opening the door or doors in an emergency.
A further known door opening system is the electric rotary operator with a lift and lock feature. Similar to the pneumatic rotary operator with the lift and lock feature discussed above, electric rotary operators with the lift and lock feature employ an electric motor to drive the spindle instead of a double acting pneumatic cylinder. Potential shortcomings of this design also include sensitivity to door panel adjustment, in addition to the binding of the locking wedges in the door-closed position caused by elastic or plastic deformation of the portal opening.
Other types of electric rotary door operators for controlling the opening and closing of doors of multi-passenger mass transit vehicles are shown in United States Patent Application Publication Nos. 2002/0178654 and 2003/0205000. These systems include a series of gears and linkages driven by an electric motor to open and close the door. A locking system is provided on the rotary operator wherein this rotary operator includes a gear pinion that can be disengaged from the gear sector of the rotary operator to allow for unlocking of the door, enabling manual egress from the vehicle. These systems are susceptible to many of the shortcomings discussed above in relation to other types of door operating systems.